For example, the capacitor in the periphery of CPU (Central Processing Unit) used for personal computers and the like is required to generate little heat at the passing of a high ripple current, suppress the fluctuation of voltage, and have a high capacitance and low ESR. In general, a plurality of aluminum solid electrolytic capacitors or tantalum solid electrolytic capacitors are used by disposing these in parallel.
This solid electrolytic capacitor comprises an aluminum foil having fine pores in the surface layer or a tantalum sintered body having fine pores in the inside, which is used as one electrode, a dielectric layer formed on the surface layer of the electrode, and the other electrode (usually a semiconductor layer) provided on the dielectric layer.
When all pore surfaces of the one electrode are covered up by the semiconductor of the other electrode, the expected capacitance as the capacitor of the one electrode can be 100% satisfied. However, not only a lot of time is necessary for covering nearly 100% of the semiconductor but also thermal stress is imposed on the element due to heat of soldering on mounting the produced capacitor on a substrate by soldering and the leakage current value (hereinafter sometimes referred to as an LC value) is increased in some cases.